Air compressing apparatus



Nov. 20, 1934. F. A. E. JE NS 1,980,997

AIR QOMPRESSING APPARATUS F'iled Oct. 20, 1932 e Sheets-Sheet 1 Nov.20, 1934. F. A. E. JENKINS AIR COMPRESSING APPARATUS 1932 6 Sheets-Sheet 2 Filed Oct F. A. E. JENKINS 1,980,997

AIR COMPRESSING APPARATUS Filed Oct. 20, 1932 6 Sheets-Sheet 5 Nov. 20, 1934.

I l I s L J m m E Nov. 20, 1934- F. A. E. JZENKINS AIR COMPRESSING APPARATUS Filed 001:. 20, 1932 6 Sheets-Sheet 4 Nov. 20, 1934. F. A. E. JENKINS 'AIR coMPRE-sme APPARATUS 6 SheetsSheet 6 Filed Oct. 20. 1952 Patented Nov. 20, 1934 UNITED STATES.

"1,980,991 AIR oomnnssmo Arr-Anne's Fredrick Alfred Edward Canterbury, near Sydney, New South Wales, Australia Applicafi 2; Serial no! 638,785 In Australia. July 14 1932! 15 Claims. (or. 23056') The general object of this invention is to provide compact self-contained and economical apparatus for compressing air for any purpose to which compressed air may be usefully appl ed. 7

g A further object is to provide apparatuswhichv will automatically restart the compressor unit should the latter have stopped and the pressure in the receiving vessel be reduced below a set minimum.

Apparatus according tothis invention includes a main reservoir for compressed air, and a smaller reservoir for air at a much higher pressure and used as a starting. medium, this smaller reservoir being hereinafter referred to as the starting reservoir; it also includes a crankless, two-cycle, double-acting main compressor unit of. novel design operating on the Diesel principle and having opposed power cylinders and one air compressing cylinder fitted with a reciprocating piston, said compressor unit being further characterized in that air compressed in the compressing cylinder is passed through the firing or power cylinders to, first, scavenge the latter and carry the gaseous productsof combustion with it into the main reservoir thus storing them under pressure with the air, and, secondly, to provide in each power cylinder 2:. charge of air to be further compressed on the outward stroke of each power piston sufficiently to raise its temperature to that required to effect combustion when the charge of oil fuel is admitted.

The apparatus also includes means, operated manually, electrically or otherwise, for initially charging the starting reservoir to the required pressure when there is no pressure or insufiicient pressure in the main reservoir. Other automatic means are providedfor maintaining the required pressure in the starting reservoir when there is pressurein the main reservoir, the last mentioned automatic means, which consists of an air-driven pump, being controlled by the pressure in the starting reservoir and actuated by air from the main reservoir.

The apparatus also includes a pair of selector valves whereby air from the charged starting reservoir is admitted to either one of the power cylinders selectively for initially starting the main compressor unit, this operation being manually controlled by a master valve, and also to re- 59 start said unit should it have stopped as a result of the resistance offered by accumulated pressure to a predetermined value in the main reservoir, or for other reason, the restarting being automatically effected by operation of the master valve per medium of an automatic control device,

on reduction of pressure in the main reservoir as the resultofutilization of air. therefrom after the compressor unit has ceased to operate. It will be observed that the initial starting and re-start ing isdependent upon the existence of sumcient air pressure in the starting reservoir.

Associated, with the compressor unit is an arrangement of cams and tappets whereby the beiorementioned pair of selector valves are actuated alternately at each. stroke of the compressor, though the connection to the starting reservoir is not made unless the master valveis opened; another pair of tappets, actuated by the same cam device, operate respectively an oil-fuel pump and a lubricating oil pump.

The last mentioned tappets are optional, as the supply of oil-fuel and lubricating oil under pressure may be provided by other means.

For compactness, the starting reservoir together with passages therefrom to the inlets of the power cylinders, is preferably built into the structure of the main reservoir whichcserves as a base or foundation for the compressor unit; this arrangement is however not essential.

The foregoing and other features of the invention are fullyand completely ascertained by the following description of "the accompanying drawings which depictapractical embodiment of the invention and in which Fig. 1 is a schematic perspective view of the complete apparatus; v

Fig. 2 is a longitudinal sectional elevation;

Fig. 3 is a sectional plan on line III, III of Fig.2,

Fig. 4 is a part cross sectional elevation on line IV, IV, of Fig. 2;

Fig. 5 is a part cross sectional elevation on (approximately) line V, V,of Fig. 2,"

Fig. 6 is a part cross sectional elevation on line VT, VI, of Fig. 2;

Fig. 7 is apart cross sectional elevationon plane VII, VII of Fig. 1, showing the master valve and its associated control device for automatic restarting;

Fig. 8 is a part cross sectional elevation on plane 10 VIII, VIII of Fig. 1 showing details of the automatic control for starting the air pump to recharge or maintain the pressure in the starting reservoir;

Fig. 9 is a longitudinal sectional elevation of the air-compressing cylinder taken on line IX, IX, of Fig. 5;

Fig. 10 is a sectional plane (to a larger scale) of the head of one of the power cylinders and the piston head in said cylinder, showing clearly 11c the arrangement of valves and passages in these parts;

Fig. 11 is a sectional elevation of portion of the reservoir structure, taken on line XI, XE of Fig. 3.

The main parts of the compressor unit comprise a central aircompressing cylinder-T12 and. two power cylinders 13 and-=13 attached respectively to the heads 12' and 12" of the air compressing,

cylinder, the outer ends of these power cylinders having heads 14 and 14' respectively which con-1.. stitute valve boxes and are formed pn. the ,upper These standards support the unit' on'a hollow struc-I ends of tubular standards 15 andl5'.

ture which constitutes the main reservoiii .137 for compressed air, and in theupper partof which is constructed the starting'ies'ervolr,18Qofl a a, stantially triangular form as clearly shown by dotted lines in Figs. 1 and 3. This starting-resen voir is comparatively small capacity. 1 i

Externally'of the reservoir structure is an elecshallow and of relatively trically operated air pump ,for supplying air;

through pipe 21'to the starting reservoir and establishing the required'initial air'pressuretherein, this pressure being utilized ii -initially starting and in automatically re-startin'g'the compressor unit.

Thereis also provided anair-driven pump 22 for automaticallysupplying air to the "starting reservoir and maintaining the pressure therein; thisair'pump is driven by air fromfthe main reservoir 17 throughpipe 23 and discharges to th starting reservoir'th'roughpipe 24. a

The details of the compressor unit are most clearly shownin Figs. 2 and 3. A hollow reciprocating piston element. comnionto' the air com- Dressing cylinder 12 andibothp 'ower cylinders, is formed in twoparts 26jand 26 fitted respectively to opposite sides .of piston 29 in the cylinder 12 and at their outer ends formed with hollow plunger '-heads 27, 27' respectively, these'fheads fitting in the powercylinders. In thesepheads 27 and 27' respectively are 'spring-loadedvalves' 28 and 28 opening outwardly. 'Near" the outer end of each part of the piston'elementis a transverse partition',13". 1 I

Both'parts of the'piston ele entare formed with double walls providing betweenthem annular spaces 30 and 30' respectively which'communicateat their outer ends through ports 31 andv 31-,with the hollow heads 27 and 27, and at their inner ends, through passages 32 and 32. formed in the piston 2 9 (Figs 2 and 4), with opposite ends respectively of.,the air compressing cylinder 12 irrespective of the position of the pis ton 29 at any time. j f

Fitting about the parts .26, 26"and forming part of the hub of piston 29 is la, double -ended cam sleeve 34 with bevelled endswhich, asjthe piston 29' is reciprocated, enter annular recesses 35, 35' in the ends respectively of the cylinder 12. This cam operates tappetgear by"me'an s of which valvemechanism is actuated as. hereinafter explained,'and al'so operates other jtappet spectively by numerals 37, 38 and 41, and in the standard 15 aresimilar passages 39 and 40 respectively (see Fig. 10).

The mechanism actuating valves 37, 41 and 37, e

41 most clearly shown in Fig. 2. In this figure,

the piston 29 is shown in its extreme position at *-the left-hand end of cylinder 12, and cam 34 having entered recess 35, tappet 44 is lifted thereby and actuatescrank-lever 45 pivoted at 46 to a bracket 47 mounted on a bridge bar 48 secured to cylinder .12.

To the upper end of crank-lever 45 there are pivotally connected two rods 49 and 50, rod 49 being adjustably connected at its other end to'cra'nk-lever 51 which engages the stem of oil-fuel needle valve 41, while rod 50 at its other end is connected to one end of pivoted lever 52 the other end of which bears upon the stem of valve 37. At the other end of cylinder 12, tappet 44 is in engagement with crank lever 45, this lever being connected to rods 49 and 50 which are similarly connected respectively to crank lever 51' actuating needle valve 41', and to lever 52 actuating the air discharge valve 37. It will thus be seen'that when the piston 29 and piston head 27 are at or near the left hand ends of their cylinders respectively, oil-fuel valve 41 at the left, and air discharge valve 37 at the right, are opened, but these valves close as those pistons move towards the right, and that when piston 29 and piston head 2'7 are at or near the right hand ends of their respective cylinders, oiliuel valve 41' and air discharge valve 37 are opened.

Disposed at right angles to the tappets 44, 44 are other tappets 54, 5'4 and 55, 55' arranged in pairs-at opposite ends of cylinder 12 ,(see Figs. 3 and 5); these tappets are actuated by the cam 34. Tappets 54,54 operate oil-fuel pumps 56 of known typeto supply oil-fuel under pressure to a receiver (not shown) whence it is conveyed to the oil-fuel valves 41, 41. Tappets 55, 55' operate pumps57 for supplying lubricating oil under pressure. These tappets54, 54 and 55, 55 are returned by springs 59.

Disposed oppositely'to tappets 44, 44 respectively are two more tappets 60, 60 also actuated alternately by cam 34, their outer ends bearing upon rocker arms 61 each of which is pivoted at one end on a bracket 62 (Fig. 5) and at its other end, in which is an adjusting screw 63, bears uponone end of a bar 64 centrally pivoted at 65. As theicarn 34 reciprocates, the tappets 60, 60 effect an oscillation of bar 64 about its pivotal point opposite ends of the bar 64, are alternately opened 1 spring 69'. This disposition will remain untilthe cam 34 has moved suflficiently to theright to release tappet 60 and engage tappet 60' and thus depress the other end of bar 64,'thereby opening valve 66', the other valve '66 automatically closing. In this position the spring d'etent 68 engages the notch 67'.

Springs 69, 69 serve no other purpose than to seat the valves 66, 66' and therefore may be of light construction so that the spring detents 68, 63 are required to do no more than hold the bar in set position (one end depressed) until this position is reversed by movement of cam 34. The retention of one admission valve in open position during this period is essential as will be explained later. 1

The position of these selector valves 66, 66 is shown by dotted circles in Fig. 3 and their function is to selectively control the flow of high pressure air from passages 70, 70' which communicate with the starting reservoir 18 through a master valve or control valve '71, to passages 72, 72' respectively which in turn communicate with port passages 40, 40' in standards 15, 15' and so through valves 38, 38' to the power cylinders. This arrangement of passages is most clearly shown in Fig. 11 which depicts in sectional elevation the passages and valves to the right of the master valve.

The master valve '71 and its regulating means indicated generally by numeral 73, are clearly shown in Fig. '7. The valve which is spring-urged to its seat, controls communication between the starting reservoir 18 and passage '70, and is opened by depression of lever 74 pivoted at one end on a bracket '75. Depression of the lever may be eifected both manually and automatically. The free end of the lever is connected by a flexible cord 76 to a stem '77 of a plate '78 fitted to a flexible diaphragm '79 which is subjected on its underside to the pressure existing at any time in the main reservoir 17 and urged against said pressure by a spring 80. While the pressure in the main reservoir is sufficient to counteract that of the spring 80, the lever 73 and valve '71 are unaffected and the valve is normally closed. Should however the pressure in the main reservoir fall to the extent that the spring pressure on the diaphragm is the greater, then the lever '74 is drawn downwardly, the valve '71 is opened, and communication is established between the starting reservoir 18 and passage '70.

The automatic means for control of the airdriven pump 22 is shown clearly in Fig. 8. An air chamber 82 is constructed in the main reservoir (see also Figs. 1, 2 and 3) and from it the pipe 23 leads to the pump 22. Chamber 82 is in communication with the main reservoir through a spring-loaded valve 83 which is opened by depression of lever 84 pivoted at one end to bracket 85. The other end of lever 84 is coupled to and actuated by a control device indicated generally by numeral 86 similar to the control device shown in and described in reference to Fig. '7, but so located that its diaphragm is subject to the pressure in the starting reservoir 18. Should this pressure fall below a set minimum the valve 83 is automatically opened and air from chamber 82 is supplied to start the air-driven pump 22for the purpose of re-establishing the required pressure in the starting reservoir. Obviously the operation of pump 22 depends on the existence of sufiicient pressure in the main reservoir. Otherwise the starting reservoir may be charged by means of pump 20.

The operation of the apparatus will now be described, it being understood that a condition precedent to starting is the establishment of high air pressure in the starting reservoir and a supply of oil fuel under pressure. Further, it will be assumed that the parts are in the relative positions shown in Fig. 2 with the exception that valve 28 in piston head 2'1 is closed instead of open as shown, this closure being the natural eiiect of the valve spring.

To start the compressor unit, the master valve '71 is opened by manual depression of lever 74, and air from the starting reservoir 18 enters passage 70, and thence passes through selector valve 66, passages 72 and 40 (Fig. 10) and valve 38 (which is opened by the air pressure) into power cylinder 13. The eitect of this air pressure is to drive the piston assembly to the right, some of the air in power cylinder 1'3being discharged through valve 37 into the main reservoir 17. When cam 34 leaves tappet 44 valve 37 closes and the remaining air in cylinder 13 is compressed.

Meantime, air is compressed in cylinder 12 by the'movemcnt of piston 29, this pressure being communicated through passages 32, annular passage 30 and ports 31 to the hollow piston head 27, but owing to excess pressure on the outside of valve 28 it cannot escape therethrough until cam 34 actuates tappet 44 to open valve 37, when the excess pressure is released and passes, to gether with the air from cylinder 12, which now opens valve 28, through valve 37 and passage 39' to the main reservoir 17.

The contact of cam 34 with tappet 44 results in opening of the oil-fuel valve 41, and if the imprisoned air in cylinder 13 is, as a result of compression after closure of valve 37', raised to a suificientfy high temperature, the oil-fuel charge from valve 41 will be fired and as a result of combustion the piston assembly will be propelled in reverse direction, thus compressing air in cylinder 12 between head 12" and piston 29. Should the required pressure and temperature to effect combustion of the oil-fuel charge, not be obtained on the first stroke, the master valve is held open and, the positions of valves 66, 66 be-- ing reversed as the result of cam 34 actuating tappet air from the starting reservoir 17 flows through valve 66' passages 72, 40 and valve 38 to cylinder 13 thus effecting a return stroke of the piston assembly, allowing valve 37 to close and compressing air in cylinder 13.

This compression is greater than on the first stroke owing to the fact that some initial pressure exists in cylinder 13 as a result of the first stroke. I

This reciprocation of the piston assembly by air from the starting reservoir is continued as required until sufficient pressure and temperature is obtained in one power cylinder to effect the required combustion ofthe oil-fuel charge, whereupon the master valve 71 is permitted to close and the compressor unit takes up normal running, a charge being fired in each power cylinder alternately.

Assuming that a charge has been fired in cylinder 13 and the piston assembly is in the position shown in Fig. 2, valve 37 being opened by the action of cam 34 on tappet 44; the pressure in cylinder 13' is equal to that in the main reservoir 17, and air compressed in cylinder 12 between head 12' and piston 29, passes by way of passages 32', annular passage 30', ports 31' and hollow piston head 27 through valve 28' into cylinder13, and through valve 3'7 into the main reservoir 17. Thus the products of combustion are scavenged from cylinder 13 and carried into the main reservoir before valve 37 is closed on the by way of passages 32 and 30, ports 31, and valve in cylinder, 13'

28 into cylinder 13, and thence through the now open'valve 37 into reservoir 17.

The automatic re-starting of the compressor unit, should the pressure in the main reservoir fall below a set minimum, is effected in a similar manner to the initial starting, except that the opening and closing of the master valve is automatically controlled by the. air pressure in the main reservoir acting on the control device .173. An air take-off for the reservoir 17 is indicated at 88 in Figure 1.

What I claim and desire to secure byLetters Patent is:

, 1. A 'crankless direct acting air compressor operating on the Diesel principle, comprising an air compressing cylinder, opposedpower cylinders extending from opposite ends of the compressing cylinder and in axial alignment therewith, said air compressing cylinder having automatic air admission valves; a reciprocating element common to all three cylinders and comprising a piston in the compressing cylinder and plungers extending in opposite directions therefrom and operating in the said power cylinders, said piston having air ducts leading from opposite sides of the compression cylinder and said plungers having air ducts leading from those of the piston, an outwardly opening valve at the outer end of each plunger and to which one of said ducts leads, so that air compressed between the piston and each head ,of the compressing cylinder is delivered into the power cylinders to scavenge the latter, and compressed air discharge ducts and valves at the outer ends of the power cylinders.

2. An air compressoras claimed in claim 1, including oil fuel admission valves at the outer ends of the power cylinders and means actuated by the reciprocating piston element to operate said valves.

3. An air compressor as claimed in claim 1, including means actuated by the reciprocating piston element to operate said valves for admitting air at high pressure into the power cylinders selectively for starting purposes.

4. An air compressor as claimed in claim 1, in which each plunger is hollow and together with the piston is provided with a duct leading from one side of the piston to a point near the outer end of the plunger extending from the opposite side of the piston and in'which each plunger is hollow and. is provided at the outer end with a spring loaded outwardly opening valve.

5. An air compressor as claimed in claim 1, including discharge valves and oil-fuel. valves, springs for closing said valves, and means for operating them comprising two sets of cam and tappet gears each set. controlling the discharge valve at the end of one power cylinder and the oil-fuel valve at the end of the other power cylinder.

6. An air compressor as claimed in claim 1, including discharge valves and oil fuel valves, springs for closing said valves and means for actuating said valves, comprising a sleeve cam on the piston element, a pair of tappets located respectively at the ends of the air compressing cyl-- inder and actuated alternately by said cam, and link and lever mechanism whereby the movement of each tappet opens a discharge valve at the end of one power cylinder and an oil-fuel valve at the end of the other power cylinder.

'7. An air compressor as claimedin claim 1, including means for admitting starting air to the power cylinders, said means comprising com pressed air supplying means, ducts connecting said supplying means with the power cylinders respectively, a selector valve in each such duct, and means actuated byreciprocation of thell ston element for opening said valves alternately.

8. An air compressor as claimed in claim 1, including means for admitting starting air to the power cylinders selectively,'said means comprisingcompressed air supplying ducts, means connecting the power cylinders respectively with said supplying means, an automatic valve in each such duct opening directly into one of the power cylinders, a pair of selector valves located one in each such duct and tappet mechanism, and means to operate such tappet mechanism actuated by reciprocation ofthe piston element, and a master valve controlling the supply of high pressure air-to said selector valves.

9. An air compressor as claimed in-claim i, including means for supplying starting air to the power cylinders respectively, said means comprising compressed air supplying means, ducts connecting said supplying means withthe power cylinders, a pair of selector valves located in as H such ducts and having stems, a centrally pivoted bar bearing at its ends respectively on the stems of said valves and tappet mechanism actuated by reciprocating. movement of the piston element tooscillate said bar and cause the same to open said valves alternately, a master-valve controlling the supply of compressed air to said selector valves,- and detent means for holding an opened selector valve in open position until the other is about to be opened. 7 I V 10. An air compressor as claimed in claim 1, including an air reservoir means for supplying said air reservoir with compressed air, a pair of spring-closed selector valves controlling the supply of compressed air from said reservoir to the power cylinders selectively for starting pur poses, means whereby saidv selector valves are opened alternately by reciprocation of the piston element, a master valve controlling the supply ofv air to said selectorvalves, a compressor for charging such reservoir, a master valve, means for automatically effecting the'opening of the said master valve and thus restarting the compressor should it have stoppedand the pressure in said air reservoir have fallen below a set minimum, said means comprising a movable element coupled to the master valve, subjected on one side to the pressure in said reservoir and a spring exerting suflioient force on the other side of. said movable element to, overcome a fluid'pressure ply of starting air to said selector Valves, a lever to actuate the same; an automatic device for opening the master valve on reduction of pressure in the airreservoir below a set minimum, and a flexible connection between the lever of the master valve and the automatic device to enable 1 All said valve to be opened manually and automatically.

12. Air compressing apparatus, as claimed, in claim 1 including an air compressor, a main air reservoir into which the compressor delivers compressed air, a second reservoir to contain a supply of air at high pressure for starting pur poses, means for initially charging the second reservoir, and means for supplying air to maintain the required pressure in the second reservoir, and means whereby the last mentioned means is automatically controlled by the pressure in the second reservoir, said means being actuated by air from the main reservoir.

13. Air compressing apparatus including a main reservoir for compressed air, a second starting reservoir incorporated therewith to contain a supply of compressed air for starting purposes, means for initially charging the second reservoir, an air compressor unit comprising a central air compressing cylinder, a piston therein, air inlet valves at each end of said cylinder, two power cylinders attached to the opposite ends of the compressing cylinder, plungers attached to opposite sides of said piston and having hollow heads fitting the power cylinders, a spring loaded valve opening outwardly in each such hollow plunger head, ducts establishing communication respectively between the interior of each plunger head and the remote end of the compressing cylinder, a valve box at the outer end of each power cylinder having two passages opening into the power cylinder, one being a discharge passage communicating with the main reservoir and the other an air inlet passage in communication with the starting reservoir, spring-loaded discharge and air inlet valves openreservoir and the power cylinders, selector valves in said ducts, a cam on the piston, tappets actuated by said cam for opening said selector valves alternately, and a master valve for controlling the supply of air from the starting reservoir to said ducts.

14. An air compressor as claimed in claim 1, including an air reservoir, means to charge the same with compressed air, a pair of selector valves controlling the supply of compressed air by said reservoir to the power cylinders for starting purposes, a master valve controlling the supply of starting air to said selector valves, a lever to actuate the same, an automatic device for opening the master valve on reduction of pressure in the air reservoir below a set minimum, and a flexible connection between the lever of the master valve and the automatic device to enable said valve to be opened manually and automatically and means controlled by the pressure in the reservoir for automatically opening the master valve on reduction of said pressure below a set minimum.

15. An air compressor as claimed in claim 1, including an air reservoir, means to charge the same with compressed air, a pair of selector valves controlling the supply of compressed air by said reservoir to the power cylinders for starting purposes, a master valve controlling the supply of starting air to said selector valves, a lever to actuate the same, an automatic device for opening the master valve on reduction of pressure in the air reservoir below a set minimum, and a flexible connection between the lever of the master valve and the automatic device to enable said valve to be opened manually and automatically, a main reservoir, a starting reservoir, an air chamber in valved communication with the main reservoir, an air driven pump supplying air at high pressure to the starting reservoir, and an automatic device subjected to the pressure in the starting reservoir and operating on reduction of pressure in the latter to open the communication valve and set the air pump in operation to reestablish the pressure in the starting reservoir.

FREDRICK ALFRED EDWARD JENKINS. 

